A touch screen, as an input media, may provide better convenience for users compared with a keyboard or a mouse. According to different implementation principles, the touch screen can be divided into resistive, capacitive, surface acoustic wave, infrared touch screen, etc. Currently, the resistive and capacitive touch screen technologies are widely used.
The capacitive touch screen is more and more popular by virtue of its higher sensitivity and true multi-touch advantages. The basic principle of the capacitive touch screen is: applying voltage in a driving line side and detecting signal changes in a detection line side. The driving line determines an X coordinate, and the detection line determines a Y coordinate. During detection, the driving lines in the X direction are progressively scanned; when scanning each row of driving lines, signal in each detection line is read. After a round of scanning, each intersection point of rows and columns can be scanned and X*Y signals are scanned. The detection method can specifically determine coordinates of multi points, and thus multi-touch can be realized. An equivalent circuit is specifically shown in FIG. 1 and includes a signal source 101, a driving line resistor 103, a mutual capacitor 102 between the driving line and the detection line, a parasitic capacitor 105 between the detection line and a common electrode layer, a detection line resistor 106, and a detection circuit 107. When a finger touches the touch screen, one part of current flows into the finger, and this is equivalent to changing of mutual capacitance between the driving line and an induction line, which causes weak current change to be detected in a detection side.
Currently, the widely used capacitive touch screen may include an add-on capacitive touch screen and an in-cell capacitive touch screen.
The add-on capacitive touch screen is separately manufactured from a liquid crystal display (LCD) and then attached to the LCD. However, currently, the add-on capacitive touch screen is gradually replaced by the in-cell capacitive touch screen due to cost, light transmittance, thickness of module and other reasons.